U.S. Pat. No. 3,811,350 is related to a sheet material trimming method and apparatus. This apparatus trims sheet material assemblages along face, head and foot edge portions. It includes a face knife located at a first trimming station and head and tail or foot knives located at a second trimming station which is spaced from the first trimming station. After a sheet material assemblage has been registered in a predetermined orientation relative to the knives at the first trimming station, the sheet material assemblage is clampingly gripped adjacent to its head and foot portions by two parallel sets of positively driven conveyor belts, i.e. timing belts, which extend from the first trimming station through the second trimming station toward a delivery station. After a sheet material assemblage has been gripped at the first trimming station by upper and lower belts of each set of conveyor belts, the face knife trims the face edge portion of the sheet material assemblage. An intermittent drive mechanism is then activated to drive the conveyor belts through a feed stroke to move the sheet material assemblage from the first trimming station to the second trimming station. At the same time, a next succeeding sheet material assemblage enters the first trimming station and is registered in a predetermined orientation relative to the knives. All three of the trim knives are then simultaneously moved through trimming strokes to the head and trail or foot edge portions of the leading sheet material assemblage at the second trimming station and to trim the head and trail portions of the leading sheet material assemblage at the first trimming station.
The conveyor belts clampingly hold the leading sheet material assemblage in registered orientation relative to the knives as it is moved from the first trimming station to the second trimming station and as it is trimmed at the second trimming station. Each set of the conveyor belts is mounted in a fixed spatial relationship with the associated one of the head and foot trim knives and can be moved transversely to the path of travel of the sheet material assemblages with the associated trim knife to adjust the distance between the head and foot trim knives to accommodate sheet material assemblages of different sizes. A center trim knife is mounted intermediate the head and foot trim knives for two-up-cutting.
EP 0 330 729 A1 is related to a rotary knife paper trimmer with long life shearing surfaces for trimming thick and shingled paper products.
Significant improvements in the life of cutting knife blades and the quality of shearing of thick multiple sheet paper products are produced in a paper trimming system having two circular rotatable knives mounted to overlap at a shearing station through which the paper products are passed. Thin steel annular disc cutting blades with teeth about the outer circumference are significantly improved in life by eliminating the effects of blade warping and non-continuous mating contact with a bed knife cutting surface in an adjacent shearing relationship that is not broken by intervention of sheared paper or out of round knife surfaces or by deflection of the cutting blade away from mating surface contact by the pressure of thick or shingled paper products. Friction and wear is reduced by inclination of the cutting blade to prevent continuous rubbing against sheared paper edges. These problems are resolved by dishing and mounting the flexible annular disc cutting knife at a small angle away from perpendicular to the axes of rotation of the knives.
Up to now, the problem of trimming all edges of sheet material assemblages, i.e., at a high speed, with a high quality at low trimming elements wear have not been resolved satisfactorily. The energy needed to trim the edges of booklets, books or sheet material assemblages is still an important factor in the technical field of trimming and further improvement is desirable.